Perhaps you should try some spelling variations:
trinh quan » trinh luat, trinh han
hieu lang » chieu sang, hieu quang, nhieu tang
hang cong » dang cong, hang nong, bang cong
cong manh » cong danh, duong manh, cong thanh
toan cao » toan tap
toan ban » van ban
ho hieu » ho chieu, hoi hieu, nho hieu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ho hieu lang - hanh ((trinh quan) or (tinh quang)) hang cong manh ((toan cao) OR (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu lang - hanh ((trinh quan) OR (tinh quang)) hang cong manh ((toan cao) OR (toan ban)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu lang - hanh ((trinh quan) or (tinh quang)) hang cong manh ((toan cao) OR (toan ban))".
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - hanh ((trinh quan) or (tinh quang)) hang cong manh ((toan cao) OR (toan ban))*.